Semiconductor device with recessed end surface of lead

ABSTRACT

A semiconductor device includes a semiconductor element, a first lead electrically connected to the semiconductor element, a sealing resin that covers the semiconductor element and a part of the first lead, and a recess formed in a surface flush with a back surface of the sealing resin. The sealing resin also has a front surface opposite to the back surface in a thickness direction, and a side surface connecting the front surface and the back surface to each other. The recess is formed, in part, by a part of the first lead that is exposed from the back surface of the sealing resin. The recess has an outer edge that forms a closed shape, as viewed in the thickness direction, within a region that includes the back surface of the sealing resin and the first lead.

FIELD

The present disclosure relates to a semiconductor device.

BACKGROUND

Conventional semiconductor devices, incorporating semiconductor elementssuch as transistors, are available in various configurations.JP-A-2013-69720, for example, discloses a semiconductor device includinga semiconductor element, a plurality of leads and a sealing resin. Theincorporated semiconductor element is mounted on one of the leads andelectrically connected to the leads. The sealing resin covers thesemiconductor element and a part of each lead. The portions of the leadsthat are exposed from the back surface and the side surface of thesealing resin provide terminal parts. In mounting the semiconductordevice to a circuit board, the terminal parts are bonded to a circuitwiring on the circuit board by soldering. Bonding surfaces of suchterminal parts are becoming smaller in response to the increasing demandfor smaller semiconductor devices. When such a semiconductor device withterminal parts having small bonding surfaces are subjected to rapidtemperature changes in use, solder may crack or come off the terminalparts due to thermal stress, which may result in a bonding failure.

SUMMARY

The present disclosure has been proposed under the above-notedcircumstances, and an object of the present disclosure is to provide asemiconductor device that is capable of preventing solder from crackingor separating from a terminal part in spite of thermal stress.

According to an aspect of the present disclosure, there is provided asemiconductor device including: a semiconductor element; a first leadelectrically connected to the semiconductor element; a sealing resinthat covers the semiconductor element and a part of the first lead,where the sealing resin includes a resin front surface, a resin backsurface opposite to the resin front surface in a thickness direction,and a resin side surface connecting the resin front surface and theresin back surface to each other; and at least one recess formed in asurface that is flush with the resin back surface. The recess may beformed at least by a part of the first lead that is exposed from theresin back surface. The recess has an outer edge that forms a closedshape, as viewed in the thickness direction, within a region thatincludes the resin back surface and the first lead.

With the above arrangements, a semiconductor device is provided with arecess formed at least by a part of the first lead exposed from thesealing resin. Thus, in bonding the first-lead to a circuit wiring usingsolder, a part of the solder is formed in the recess. This cancontribute to reducing formation of a crack in the solder or separationof the solder from the first lead due to thermal stress.

Other features and advantages of the present disclosure will becomeapparent from the detailed description given below with reference to theaccompanying drawings.

DRAWINGS

FIG. 1 is a perspective view showing a semiconductor device according toa first embodiment of the present disclosure;

FIG. 2 is a plan view of the semiconductor device shown in FIG. 1;

FIG. 3 is a front view of the semiconductor device shown in FIG. 1;

FIG. 4 is a bottom view of the semiconductor device shown in FIG. 1;

FIG. 5 is a rear view of the semiconductor device shown in FIG. 1;

FIG. 6 is a right side view of the semiconductor device shown in FIG. 1;

FIG. 7 is a left side view of the semiconductor device shown in FIG. 1;

FIG. 8 is a sectional view taken along line VIII-VIII in FIG. 2;

FIG. 9 is a sectional view taken along line IX-IX in FIG. 2;

FIG. 10 is a sectional view showing a part of FIG. 9 as enlarged;

FIG. 11 is a perspective view of the semiconductor device shown in FIG.1;

FIG. 12 is a plan view for describing a process for manufacturing thesemiconductor device shown in FIG. 1;

FIG. 13 is a plan view for describing the process for manufacturing thesemiconductor device shown in FIG. 1;

FIG. 14 is a plan view showing the semiconductor device of FIG. 1 asmounted on a circuit board;

FIG. 15 is a schematic sectional view taken along lines XV-XV in FIG.14;

FIG. 16 is a perspective view showing a part of the semiconductor deviceof FIG. 1 as mounted on a circuit board;

FIG. 17 is a perspective view showing a semiconductor device accordingto a second embodiment of the present disclosure;

FIG. 18 is a perspective view showing a semiconductor device accordingto a third embodiment of the present disclosure;

FIG. 19 is a perspective view showing a semiconductor device accordingto a fourth embodiment of the present disclosure;

FIG. 20 is a perspective view showing a semiconductor device accordingto a fifth embodiment of the present disclosure;

FIG. 21 is a perspective view showing a semiconductor device accordingto a sixth embodiment of the present disclosure;

FIG. 22 is a perspective view showing a semiconductor device accordingto a seventh embodiment of the present disclosure;

FIG. 23 is a bottom view showing a semiconductor device according to aneighth embodiment of the present disclosure;

FIG. 24 is a bottom view showing a semiconductor device according to aninth embodiment of the present disclosure;

FIG. 25 is an enlarged sectional view showing a part of a semiconductordevice according to a tenth embodiment of the present disclosure;

FIG. 26 is a front view showing a semiconductor device according to aneleventh embodiment of the present disclosure;

FIG. 27 is a bottom view showing the semiconductor device according tothe eleventh embodiment of the present disclosure;

FIG. 28 is a perspective view showing the semiconductor device accordingto the eleventh embodiment of the present disclosure;

FIG. 29 is a bottom view showing a semiconductor device according to atwelfth embodiment of the present disclosure; and

FIG. 30 is a perspective view showing the semiconductor device accordingto the twelfth embodiment of the present disclosure.

EMBODIMENTS

Embodiments of the present disclosure are described below with referenceto the accompanying drawings.

A semiconductor device A1 according to a first embodiment of the presentdisclosure is described below with reference to FIGS. 1-11. Thesemiconductor device A1 includes a plurality of leads 1-3, asemiconductor element 6, bonding wires 71, 72 and a sealing resin 8.

FIG. 1 is a perspective view of the semiconductor device A1. FIG. 2 is aplan view of the semiconductor device A1. In FIG. 2, for the convenienceof understanding, the semiconductor device A1 as seen through thesealing resin 8 is depicted, with the outline of the sealing resin 8depicted by a two-dot chain line. FIG. 3 is a front view of thesemiconductor device A1. FIG. 4 is a bottom view of the semiconductordevice A1. FIG. 5 is a rear view of the semiconductor device A1. FIG. 6is a right side view of the semiconductor device A1. FIG. 7 is a leftside view of the semiconductor device A1. FIG. 8 is a sectional viewtaken along line VIII-VIII in FIG. 2. FIG. 9 is a sectional view takenalong line IX-IX in FIG. 2. FIG. 10 is a sectional view showing a partof FIG. 9 as enlarged. FIG. 11 is a perspective view showing thesemiconductor device A1, with its bottom side up.

The semiconductor device A1 is configured to be surface-mounted oncircuit boards of various apparatuses. The semiconductor device A1 isrectangular as viewed in a thickness direction. For convenience ofdescription, the thickness direction of the semiconductor device A1 isreferred to as the z direction, the direction perpendicular to the zdirection and along one side of the semiconductor device (i.e.,horizontal direction in FIG. 2) is referred to as the x direction, andthe direction perpendicular to both the z direction and the x direction(i.e., vertical direction in FIG. 2) is referred to as the y direction.The size of the semiconductor device A1 is not particularly limited. Inthe present embodiment, the dimension in the x direction is about 4 to 5mm, the dimension in the y direction is about 5 to 6 mm, and thedimension in the z direction is about 0.5 to 1 mm.

The leads 1-3 support and/or are electrically connected to thesemiconductor element 6. The leads 1-3 may be formed by punching orbending a metal plate. The leads 1-3 are made of a metal, preferably Cuor Ni, an alloy of these metals, or Alloy 42, for example. In thepresent embodiment, the case where the leads 1-3 are made of Cu isdescribed as an example. The thickness of the leads 1-3 may be 0.08 to0.3 mm, for example, and is about 0.25 mm in the present embodiment.Hereinafter, the leads 1, 2 and 3 are referred to as a first lead 1, asecond lead 2 and a third lead 3, respectively, or collectively referredto as leads 1-3.

As shown in FIG. 2, the third lead 3 is arranged at a position offsettoward one of the ends of the semiconductor device A1 in they direction(upper end in FIG. 2) and spreads substantially along the entiredimension of the semiconductor device A1 in the x direction. The firstlead 1 and the second lead 2 are arranged on the other end (lower end inFIG. 2) of the semiconductor device A1 in the y direction and spacedapart from the third lead 3. The first lead 1 and the second lead 2 arearranged next to each other and spaced apart from each other in the xdirection. As viewed in the z direction, the third lead 3 is thelargest, and the first lead 1 is the smallest.

The third lead 3 includes a mount part 310, third-lead terminal parts320 and a third-lead thin part 330.

The mount part 310 is located at the center of the third lead 3 andgenerally rectangular as viewed in the z direction. The mount part 310has a mount-part front surface 311 and a mount-part back surface 312.The mount-part front surface 311 and the mount-part back surface 312face opposite to each other in the z direction. The mount-part frontsurface 311 is the surface that faces upward in FIGS. 3 and 5 to 7. Onthe mount-part front surface 311, the semiconductor element 6 ismounted. The mount-part back surface 312 is the surface that facesdownward in FIGS. 3 and 5-7. The mount-part back surface 312 is exposedfrom the sealing resin 8 to provide a back-surface terminal.

Each of the third-lead terminal parts 320 is connected to the mount part310 and generally rectangular as viewed in the z direction. In thepresent embodiment, six third-lead terminal parts 320 are provided.Specifically, one of the third-lead terminal parts 320 is arranged onone of the end surfaces of the mount part 310 in the x direction and ata position offset toward one end in the y direction (downward in FIG.2). Another one of the third-lead terminal parts 320 is arranged on theother end surface of the mount part 310 in the x direction and at aposition offset toward the one end in the y direction. The remainingfour third-lead terminal parts 320 are arranged at regular intervals onone of the end surfaces of the mount part 310 in the y direction (theupper end surface in FIG. 2). Each of the third-lead terminal parts 320has a third-lead terminal-part front surface 321, a third-leadterminal-part back surface 322 and a third-lead terminal-part endsurface 323. The third-lead terminal-part front surface 321 and thethird-lead terminal-part back surface 322 face opposite to each other inthe z direction. The third-lead terminal-part front surface 321 is thesurface that faces upward in FIGS. 3 and 5-7. The third-leadterminal-part front surface 321 is flush with the mount-part frontsurface 311. The third-lead terminal-part back surface 322 is thesurface that faces downward in FIGS. 3 and 5-7. The third-leadterminal-part back surface 322 is flush with the mount-part back surface312. The third-lead terminal-part end surface 323 faces outward andconnects the third-lead terminal-part front surface 321 and thethird-lead terminal-part back surface 322 to each other. The third-leadterminal-part end surface 323 is on the outside of the sealing resin 8.The third-lead terminal-part back surface 322 and the third-leadterminal-part end surface 323 are exposed from the sealing resin 8 andconnected to each other to provide a terminal (see FIGS. 8 and 9).

The third-lead thin part 330 is connected to the mount part 310 andarranged to surround the mount part 310 as viewed in the z direction.The thickness (i.e., the dimension in the z direction) of the third-leadthin part 330 is about a half of the thickness of the mount part 310.The third-lead thin part 330 is formed by half etching, for example. Thethird-lead thin part 330 has a third-lead thin-part front surface 331and a third-lead thin-part back surface 332. The third-lead thin-partfront surface 331 and the third-lead thin-part back surface 332 faceopposite to each other in the z direction. The third-lead thin-partfront surface 331 is the surface that faces upward in FIGS. 3 and 5-7.The third-lead thin-part front surface 331 is flush with the mount-partfront surface 311. Thus, the mount-part front surface 311, thethird-lead terminal-part front surfaces 321 and the third-lead thin-partfront surface 331 are flush and integral with each other (see FIG. 2).The third-lead thin-part back surface 332 is the surface that facesdownward in FIGS. 3 and 5-7.

All the surfaces of the third lead 3 except the third-lead terminal-partend surfaces 323 are formed with a plating layer (not shown). Theplating layer may be a lamination of a Ni plating layer, a Pd platinglayer and a Au plating layer, for example. In such a case, the Niplating layer may be 0.5 μm to 2.0 μm in thickness, the Pd plating layermay be 0.02 μm to 0.15 μm in thickness, and the Au plating layer may be0.003 μm to 0.015 μm in thickness. The configuration of the platinglayer is not limited to this and may be a lamination of a Ni platinglayer and a Au plating layer, for example. As will be described later,in the manufacturing process, a plating layer is formed on the entiresurface of a lead frame. The third-lead terminal-part end surfaces 323are the surfaces provided by cutting the lead frame, and hence, do nothave a plating layer on them.

The first lead 1 is arranged at a corner (lower right corner in FIG. 2)of the semiconductor device A1 as viewed in the z direction and includesa wire bonding part 110, a first-lead terminal part 120 and a first-leadconnecting part 130.

The wire bonding part 110 is rectangular as viewed in the z directionand located closer to the third lead 3 than other portions of the firstlead 1 are. The wire bonding part 110 has a wire-bonding-part frontsurface 111 and a wire-bonding-part back surface 112. Thewire-bonding-part front surface 111 and the wire-bonding-part backsurface 112 face opposite to each other in the z direction. Thewire-bonding-part front surface 111 is the surface that faces upward inFIGS. 3 and 5-7. The bonding wire 71 is bonded to the wirebonding-part-front surface 111. The wire-bonding-part back surface 112is the surface that faces downward in FIGS. 3 and 5-7. The thickness(i.e., the dimension in the z direction) of the wire bonding part 110 isabout a half of the thickness of the first-lead terminal part 120. Thewire bonding part 110 is formed by half etching, for example.

The first-lead terminal part 120 is located on the opposite side of thethird lead 3 with respect to the wire bonding part 110 and on the outerside in the y direction. The first-lead terminal part 120 has afirst-lead terminal-part front surface 121, a first-lead terminal-partback surface 122, a first-lead terminal-part end surface 123 and afirst-lead terminal-part second end surface 124. The first-leadterminal-part front surface 121 and the first-lead terminal-part backsurface 122 face opposite to each other in the z direction. Thefirst-lead terminal-part front surface 121 is the surface that facesupward in FIGS. 3 and 5-7. The first-lead terminal-part back surface 122is the surface that faces downward in FIGS. 3 and 5-7. The first-leadterminal-part end surface 123 faces outward in the y direction andconnects the first-lead terminal-part front surface 121 and thefirst-lead terminal-part back surface 122 to each other. The first-leadterminal-part end surface 123 is on the outside of the sealing resin 8.The first-lead terminal-part back surface 122 and the first-leadterminal-part end surface 123 are exposed from the sealing resin 8 andconnected to each other to provide a terminal (see FIG. 9). Thefirst-lead terminal-part second end surface 124 faces away from thefirst-lead terminal-part end surface 123, is exposed from the sealingresin 8 and is connected to the first-lead terminal-part back surface122 (see FIGS. 10 and 11).

The first-lead connecting part 130 is connected to the wire bonding part110 and the first-lead terminal part 120 to connect the wire bondingpart 110 and the first-lead terminal part 120 to each other. Thefirst-lead connecting part 130 is rectangular as viewed in the zdirection. The thickness (i.e., the dimension in the z direction) of thefirst-lead connecting part 130 is about a half of the thickness of thefirst-lead terminal part 120 and the same as that of the wire bondingpart 110. The first-lead connecting part 130 is formed by half etching,for example. The width (the dimension in the x direction) of thefirst-lead connecting part 130 is smaller than the width of the wirebonding part 110 and the same as the width of first-lead terminal part120 at the end adjoining the first-lead connecting part 130. Thefirst-lead connecting part 130 has a first-lead connecting-part frontsurface 131 and a first-lead connecting-part back surface 132. Thefirst-lead connecting-part front surface 131 and the first-leadconnecting-part back surface 132 face opposite to each other in the zdirection. The first-lead connecting-part front surface 131 is thesurface that faces upward in FIGS. 3 and 5-7. The first-leadconnecting-part front surface 131, the wire-bonding-part front surface111 and the first-lead terminal-part front surface 121 are flush andintegral with each other (see FIGS. 2, 9 and 10). The first-leadconnecting-part back surface 132 is the surface that faces downward inFIGS. 3 and 5-7. The first-lead connecting-part back surface 132 isflush with the wire-bonding-part back surface 112 and located closer toa resin front surface 81 than the first-lead terminal-part back surface122 is (see FIGS. 10 and 11). The first-lead connecting-part backsurface 132 is exposed from the sealing resin 8 and connected to thefirst-lead terminal-part second end surface 124 (see FIGS. 10 and 11).The first-lead connecting-part back surface 132 may not be entirelyexposed from the sealing resin 8, and only a part of the first-leadconnecting-part back surface 132 may be exposed from the sealing resin8.

All the surfaces of the first lead 1 except the first-lead terminal-partend surface 123 are formed with a plating layer (see FIG. 10). Theplating layer 140 is the same plating layer as that of the third lead 3and may be a lamination of a Ni plating layer, a Pd plating layer and aAu plating layer, for example. The configuration of the plating layer isnot limited to this. As will be described later, in the manufacturingprocess, a plating layer is formed on the entire surface of a leadframe. The first-lead terminal-part end surface 123 is the surfaceprovided by cutting the lead frame, and hence, do not have the platinglayer 140 on it.

As shown in FIGS. 4, 9, 10 and 11, the first lead 1 has a recess 126 inthe first-lead terminal-part back surface 122. The recess 126 iscircular as viewed in the z direction and located at or near the centerof the first-lead terminal-part back surface 122. The outer edge of therecess 126 forms a closed shape within the first-lead terminal-part backsurface 122. The recess 126 is formed by half etching or stamping, forexample. The shape, number and arrangement of the recess 126 may bevaried. The recess 126 is also formed with the plating layer 140 (seeFIG. 10).

As shown in FIGS. 1, 2, 4, 9, 10 and 11, the first lead includes anend-surface recess 127 in the first-lead terminal-part end surface 123.The end-surface recess 127 extends from one end to the other end of thefirst-lead terminal-part end surface 123 in the z direction. As will bedescribed later, the end-surface recess 127 is formed by making athrough-hole in a lead frame followed by cutting the lead frame at thethrough-hole in the manufacturing process. The first-lead terminal-partend surface 123, which is the cut surface, is not formed with theplating layer 140, but the end-surface recess 127 is formed with theplating layer 140 (see FIG. 10).

The second lead 2 is arranged at a corner (lower left corner in FIG. 2)of the semiconductor device A1 as viewed in the z direction. The secondlead 2 includes a wire bonding part 210, three second-lead terminalparts 220 and three second-lead connecting parts 230.

The wire bonding part 210 is in the form of a rectangle elongated in thex direction as viewed in the z direction and located closer to the thirdlead 3 than other portions of the second lead 2 are. The wire bondingpart 210 has a wire-bonding-part front surface 211 and awire-bonding-part back surface 212. The wire-bonding-part front surface211 and the wire-bonding-part back surface 212 face opposite to eachother in the z direction. The wire-bonding-part front surface 211 is thesurface that faces upward in FIGS. 3 and 5-7. The bonding wires 72 arebonded to the wire bonding-part-front surface 211. The wire-bonding-partback surface 212 is the surface that faces downward in FIGS. 3 and 5-7.The thickness (i.e., the dimension in the z direction) of the wirebonding part 210 is about a half of the thickness of the second-leadterminal parts 220. The wire bonding part 210 is formed by half etching,for example.

The three second-lead terminal parts 220 are located on the oppositeside of the third lead 3 with respect to the wire bonding part 210 andon the outer side in the y direction. The second-lead terminal parts 220are arranged side by side at regular intervals in the x direction. Eachof the second-lead terminal parts 220 has the same configuration as thatof the first-lead terminal part 120. Specifically, each second-leadterminal part 220 has a second-lead terminal-part front surface 221, asecond-lead terminal-part back surface 222, a second-lead terminal-partend surface 223 and a second-lead terminal-part second end surface 224.The second-lead terminal-part front surface 221 and the second-leadterminal-part back surface 222 face opposite to each other in the zdirection. The second-lead terminal-part front surface 221 is thesurface that faces upward in FIGS. 3 and 5-7. The second-leadterminal-part back surface 222 is the surface that faces downward inFIGS. 3 and 5-7. The second-lead terminal-part end surface 223 facesoutward in the y direction and connects the second-lead terminal-partfront surface 221 and the second-lead terminal-part back surface 222 toeach other. The second-lead terminal-part end surface 223 is on theoutside of the sealing resin 8. The second-lead terminal-part backsurface 222 and the second-lead terminal-part end surface 223 areexposed from the sealing resin 8 and connected to each other to providea terminal. The second-lead terminal-part second end surface 224 facesaway from the second-lead terminal-part end surface 223, is exposed fromthe sealing resin 8 and is connected to the second-lead terminal-partback surface 222.

The second-lead connecting parts 230 connect the second-lead terminalparts 220 and the wire bonding part 210 to each other. Specifically, thethree second-lead connecting parts 230, which are connected to the wirebonding part 210, are connected to the three second-lead terminal parts220, respectively. Each of the second-lead connecting parts 230 isrectangular as viewed in the z direction. The thickness (i.e., thedimension in the z direction) of the second-lead connecting parts 230 isabout a half of the thickness of the second-lead terminal parts 220 andthe same as that of the wire bonding part 210. The second-leadconnecting parts 230 are formed by half etching, for example. The width(i.e., the dimension in the x direction) of each second-lead connectingpart 230 is the same as the width of each second-lead terminal part 220at the end adjoining the second-lead connecting part 230. Each of thesecond-lead connecting parts 230 has a second-lead connecting-part frontsurface 231 and a second-lead connecting-part back surface 232. Thesecond-lead connecting-part front surface 231 and the second-leadconnecting-part back surface 232 face opposite to each other in the zdirection. The second-lead connecting-part front surface 231 is thesurface that faces upward in FIGS. 3 and 5-7. The second-leadconnecting-part front surfaces 231, the wire-bonding-part front surface211 and the second-lead terminal-part front surfaces 221 are flush andintegral with each other (see FIG. 2). The second-lead connecting-partback surface 232 is the surface that faces downward in FIGS. 3 and 5-7.The second-lead connecting-part back surface 232 is flush with thewire-bonding-part back surface 212 and located closer to the resin frontsurface 81 than the second-lead terminal-part back surface 222 is. Thesecond-lead connecting-part back surface 232 is exposed from the sealingresin 8 (see FIG. 4) and connected to the second-lead terminal-partsecond end surface 224. The second-lead connecting-part back surface 232may not be entirely exposed from the sealing resin 8, and only a part ofthe second-lead connecting-part back surface 232 may be exposed from thesealing resin 8.

All the surfaces of the second lead 2 except the second-leadterminal-part end surfaces 223 are formed with a plating layer. Theplating layer is the same as the plating layer 140 of the first lead 1and may be a lamination of a Ni plating layer, a Pd plating layer and aAu plating layer, for example. The configuration of the plating layer isnot limited to this. As will be described later, in the manufacturingprocess, a plating layer is formed on the entire surface of a leadframe. The second-lead terminal-part end surfaces 223 are the surfacesprovided by cutting the lead frame, and hence, do not have a platinglayer on them.

As shown in FIG. 4, the second lead 2 has a recess 226 in each of thesecond-lead terminal-part back surfaces 222. The recess 226 is circularas viewed in the z direction and located at or near the center of thesecond-lead terminal-part back surface 222. The outer edge of the recess226 forms a closed shape within the second-lead terminal-part backsurface 222. The recess 226 is formed by half etching or stamping, forexample. The shape, number and arrangement of the recess 226 may bevaried. The recess 226 is also formed with a plating layer.

As shown in FIGS. 1, 2 and 4, the second lead 2 also includes anend-surface recess 227 formed in the second-lead terminal-part endsurface 223. The end-surface recess 227 extends from one end to theother end of the second-lead terminal-part end surface 223 in the zdirection. As will be described later, the end-surface recess 227 isformed by making a through-hole in a lead frame followed by cutting thelead frame at the through-hole in the manufacturing process. Thesecond-lead terminal-part end surface 223, which is the cut surface, isnot formed with the plating layer, but the end-surface recess 227 isformed with the plating layer.

The semiconductor element 6 is an element that performs electricalfunctions of the semiconductor device A1. The type of the semiconductorelement 6 is not particularly limited. In the present embodiment, thesemiconductor element 6 is a transistor such as a MOSFET(metal-oxide-semiconductor field-effect transistor). The semiconductorelement 6 includes an element body 60, a first electrode 61, a secondelectrode 62 and a third electrode 63 (see FIG. 5).

As shown in FIG. 2, for example, the first electrode 61 and the secondelectrode 62 are provided on a (first) surface of the element body 60that faces away from the third lead 3. As shown in FIG. 5, the thirdelectrode 63 is disposed on another (or second) surface of the elementbody 60 that faces the third lead 3. In the present embodiment, thefirst electrode 61 is a gate electrode, the second electrode 62 is asource electrode, and the third electrode 63 is a drain electrode. Inthe illustrated example, the third electrode 63 is formed on theentirety of the above-mentioned second surface of the element body 60,though the present disclosure is not limited to this configuration. Forinstance, the third electrode 63 may cover only a predetermined limitedarea of the above-mentioned second surface of the element body 60.

The semiconductor element 6 is mounted at the center of the mount-partfront surface 311 of the third lead 3 using an electroconductive bondingmaterial. Thus, the third electrode 63 of the semiconductor element 6 iselectrically connected to the third lead 3 via the electroconductivebonding material. The bonding wire 71 is connected to the firstelectrode 61 of the semiconductor element 6 and the wire-bonding-partfront surface 111 of the first lead 1. Thus, the first electrode 61 ofthe semiconductor element 6 is electrically connected to the first lead1. The bonding wires 72 are connected to the second electrode 62 of thesemiconductor element 6 and the wire-bonding-part front surface 211 ofthe second lead 2. Thus, the second electrode 62 of the semiconductorelement 6 is electrically connected to the second lead 2.

The configuration of the semiconductor element 6 and the method forconnecting the semiconductor element 6 to the leads 1-3 described aboveare merely an example. The type, number and arrangement of thesemiconductor element 6 as well as the connection method may be varied.

The sealing resin 8 covers the semiconductor element 6, the bondingwires 71 and 72, and a part of each lead 1-3. The sealing resin 8 may beformed of a black epoxy resin.

The sealing resin 8 has a resin front surface 81, a resin back surface82 and a resin side surface 83. The resin front surface 81 and the resinback surface 82 face opposite to each other in the z direction. Theresin front surface 81 is the surface that faces upward in FIGS. 3 and5-7. The resin back surface 82 is the surface that faces downward inFIGS. 3 and 5-7. The resin side surface 83 is the surface that connectsthe resin front surface 81 and the resin back surface 82 to each otherand faces in the x direction or the y direction. The resin side surface83 includes a first side surface 831 and a second side surface 832. Thesecond side surface 832 is connected to the resin back surface 82 andparallel to the x-z plane or the y-z plane. The first side surface 831is connected to the resin front surface 81 and inclined with respect tothe x-z plane or the y-z plane.

In the present embodiment, the first-lead terminal part 120, thesecond-lead terminal parts 220 and the third-lead terminal parts 320project from the second side surface 832 of the resin side surface 83.The first-lead terminal-part end surface 123 including the end-surfacerecess 127, the second-lead terminal-part end surfaces 223 including theend-surface recesses 227, and the third-lead terminal-part end surfaces323 are exposed from the second side surface 832 of the resin sidesurface 83. The first-lead terminal-part back surface 122, thesecond-lead terminal-part back surfaces 222, the third-leadterminal-part back surfaces 322 and the mount-part back surface 312 ofthe third lead 3 are flush with the resin back surface 82 of the sealingresin 8. The recess 126 of the first-lead terminal part 120 and therecesses 226 of the second-lead terminal parts 220 are exposed from theresin back surface 82 of the sealing resin 8.

In forming the sealing resin in the manufacturing process, use is madeof a mold that is configured such that the sealing resin will not coverthe first-lead connecting-part back surface 132 and the first-leadterminal-part second end surface 124 as well as the second-leadconnecting-part back surface 232 and the second-lead terminal-partsecond end surface 224. Thus, the resulting sealing resin 8 has interiorside surfaces 84 that are perpendicular to the first-leadconnecting-part back surface 132 and the second-lead connecting-partback surfaces 232 and that surround the first-lead connecting-part backsurface 132 or the second-lead connecting-part back surfaces 232 (seeFIGS. 10 and 11). The first-lead connecting-part back surface 132 andthe first-lead terminal-part second end surface 124 as well as thesecond-lead connecting-part back surfaces 232 and the second-leadterminal-part second end surfaces 224 are exposed from the resin backsurface 82 of the sealing resin. The first-lead connecting-part backsurface 132, the first-lead terminal-part second end surface 124 andinterior side surfaces 84 of the sealing resin 8 define a recess 85 (seeFIGS. 10 and 11). Also, each of the second-lead connecting-part backsurface 232, each of the second-lead terminal-part second end surfaces224 and interior side surfaces 84 of the sealing resin 8 define a recess85. The outer edge of each recess 85 forms a closed shape within theresin back surface 82.

A method for manufacturing the semiconductor device A1 is describedbelow with reference to FIGS. 12 and 13.

First, a lead frame 10 is prepared, as shown in FIG. 12. The lead frame10 is a plate-like material for providing the leads 1-3. The lead frame10 has a front surface 1010 for providing the wire-bonding-part frontsurface 111, the first-lead terminal-part front surface 121, thefirst-lead connecting-part front surface 131, the wire-bonding-partfront surface 211, the second-lead terminal-part front surfaces 221, thesecond-lead connecting-part front surfaces 231, the mount-part frontsurface 311, the third-lead terminal-part front surfaces 321 and thethird-lead thin part 331. The front surface 1010 of the lead frame 10 isentirely flat. Indicated by relatively dense hatching in FIG. 12 is aregion that has a larger thickness (dimension in the z direction) andprovides the first-lead terminal part 120, the second-lead terminalparts 220, the mount part 310 and the third-lead terminal parts 320.Indicated by relatively coarse hatching in FIG. 12 is a region that hasa smaller thickness (dimension in the z direction) and provides the wirebonding part 110, the first-lead connecting part 130, the recesses 126,the wire bonding part 210, the second-lead connecting parts 230, therecesses 226 and the third-lead thin part 330. This region is formed byhalf etching, for example. The recesses 126 and 226 may be formed bystamping.

The lead frame 10 is also formed with through-holes 1020 to provide theend-surface recesses 127 and 227 at the regions that provide thefirst-lead terminal part 120 and the second-lead terminal parts 220. Inthe present embodiment, the base material for the lead frame 10 is Cu.The surfaces of the lead frame 10 are formed with a plating layer. Theplating layer may be a lamination of a Ni plating layer, a Pd platinglayer and a Au plating layer, for example. The plating layer is formedon the entire surface of the lead frame 10, including the inner walls ofthe through-holes 1020 and the inner surfaces of the recesses 126 and226.

Next, as shown in FIG. 13, the semiconductor element 6 is bonded to themount part 310 of the lead frame 10 with an electroconductive bondingmaterial. Then, a bonding wire 71 is bonded to the first electrode 61 ofthe semiconductor element 6 and the wire bonding part 110 of the firstlead 1, while a plurality of bonding wires 72 are bonded to the secondelectrode 62 of the semiconductor element 6 and the wire bonding part210 of the second lead 2.

Then, a resin material is cured to form the sealing resin 8 (indicatedby single-dot chain line in FIG. 12) that covers a part of the leadframe 10, the semiconductor element 6 and the bonding wires 71 and 72.The lead frame 10 is then cut along the cut line 1030, which extendsacross the through-holes 1020. This cutting process provides thefirst-lead terminal-part end surface 123 and the second-leadterminal-part end surfaces 223, which are the cut surfaces, as well asthe end-surface recesses 127 and 227 defined by portions of the innerwalls of the through-holes 1020. Since the first-lead terminal-part endsurface 123 and the second-lead terminal-part end surfaces 223 are cutsurfaces provided by cutting, they are not formed with the plating layer140. Meanwhile, the end-surface recess 127 and 227 are formed with theplating layer 140.

In this way, the semiconductor device A1 is obtained.

Next, mounting of the semiconductor device A1 on a circuit board isdescribed. FIGS. 14-16 are the views for describing mounting of thesemiconductor device A1 on a circuit board 9. FIG. 14 is a plan viewshowing the semiconductor device A1 mounted on a circuit board 9. FIG.15 is a schematic sectional view taken along lines XV-XV in FIG. 14.FIG. 16 is a perspective view showing the semiconductor device A1mounted on the circuit board 9. Note that FIG. 16 shows the state asseen through the sealing resin 8, and the portions of the first lead 1that are actually hidden by the sealing resin 8 are depicted by brokenlines.

As shown in FIG. 14, the semiconductor device A1 is mounted on a circuitboard 9, and the terminals of the semiconductor device A1 are bonded toa circuit wiring 91 formed on the circuit board 9 with solder 92.Specifically, the first-lead terminal part 120 is bonded to a circuitwiring 911, the three second-lead terminal parts 220 are bonded to acircuit wiring 912, and the third-lead terminal parts 320 are bonded toa circuit wiring 913. Note that, though not shown in FIG. 14, themount-part back surface 312 of the third lead 3 is also bonded to thecircuit wiring 913 with solder 92. In this way, solder 92 is providedbetween the circuit wiring 91 and the first-lead terminal part 120, thesecond-lead terminal parts 220 or the third-lead terminal parts 320.

FIGS. 15 and 16 show solder 92 formed between the first-lead terminalpart 120 and the circuit wiring 91. Note that the solder 92 formedbetween each of the second-lead terminal parts 220 and the circuitwiring 91 have the same configuration as that shown in these figures.The solder 92 includes a first solder fillet 921, a second solder fillet922 and a filling part 923. The first solder fillet 921 is formed on theouter side of the first-lead terminal part 120 in the y direction. Sincethe first-lead terminal-part end surface 123 is not formed with aplating layer 140, it has limited solder wettability. Thus, the firstsolder fillet 921 is mainly formed in the end-surface recess 127 formedwith the plating layer 140.

The second solder fillet 922 is formed on the inner side of thefirst-lead terminal part 120 in the y direction. As described above, therecess 85 exists on the inner side of the first-lead terminal part 120in the y direction. In the recess 85, the first-lead connecting-partback surface 132 and the first-lead terminal-part second end surface124, which are formed with the plating layer 140, are exposed from thesealing resin 8. This allows the second solder fillet 922 to be formedin the recess 85 and mainly on the first-lead terminal-part second endsurface 124. The filling part 923 is a portion of the solder 92 thatfills the recess 126.

The advantages of the semiconductor device A1 are described below.

In the above embodiment, the first lead 1 has the recess 126 in thefirst-lead terminal-part back surface 122. In bonding the first-leadterminal part 120 to the circuit wiring 91 using the solder 92, thesolder fills the recess 126, forming the filling part 923. Thus, theexistence of the recess 126 increases the bond area between thefirst-lead terminal part 120 and the solder 92. This reduces formationof a crack in the solder 92 or separation of the solder 92 from thefirst-lead terminal-part back surface 122 due to thermal stress.Likewise, the second lead 2 has the recess 226 in each of thesecond-lead terminal-part back surfaces 222. This reduces formation of acrack in the solder 92 or separation of the solder 92 from thesecond-lead terminal-part back surface 222 due to thermal stress.

Also, in the above embodiment, the recess 85 is provided on the innerside of the first-lead terminal part 120 in the y direction. In bondingthe first-lead terminal part 120 to the circuit wiring 91 using thesolder 92, the solder fills the recess 85, forming the second solderfillet 922. This also contributes to reduction of formation of a crackin the solder or separation of the solder 92 from the first-leadterminal-part back surface 122 due to thermal stress. Likewise, therecess 85 is also provided on the inner side of each second-leadterminal part 220 in the y direction. This contributes to reduction offormation of a crack in the solder or separation of the solder 92 fromthe second-lead terminal-part back surface 222 due to thermal stress.

Moreover, in the above embodiment, the first lead 1 has the end-surfacerecess 127 in the first-lead terminal-part end surface 123. Theend-surface recess 127, which is formed with the plating layer 140,allows a sufficiently large fillet (the first solder fillet 921) to beformed on the outer side of the first-lead terminal part 120 in the ydirection, though the first-lead terminal-part end surface 123 is notformed with the plating layer 140. This also contributes to reduction offormation of a crack in the solder 92 or separation of the solder 92from the first-lead terminal-part back surface 122 due to thermalstress. Likewise, the second lead 2 has the end-surface recess 227 ineach of the second-lead terminal-part end surfaces 223. This alsocontributes to reduction of formation of a crack in the solder 92 orseparation of the solder 92 from the second-lead terminal-part backsurface 222 due to thermal stress.

Note that the first solder fillet 921 is formed on the first-leadterminal-part end surface 123 and the second-lead terminal-part endsurfaces 223 even if these surfaces do not have the end-surface recesses127 and 227. Thus, the end-surface recesses 127 and 227 are notnecessarily required. However, to form a larger first solder fillet 921on the outer side of the first-lead terminal part 120 and thesecond-lead terminal parts 220 in the y direction, it is desirable toform the end-surface recesses 127 and 227.

A surface plating layer may be formed on all the portions of each lead1-3 that are exposed from the sealing resin 8. The surface plating layeris made of a material having higher solder wettability than that of thebase material for the leads 1-3 and is made of Au, for example. Thesurface plating layer is formed by displacement electroless plating.When such a surface plating layer is formed on the first-leadterminal-part end surface 123 and/or the second-lead terminal-part endsurfaces 223, solder easily adheres to the first-lead terminal-part endsurface 123 and/or the second-lead terminal-part end surfaces 223, whichallows for formation of larger first solder fillets 921. In this case,the end-surface recesses 127 and 227 need not be formed.

In the above embodiment, the case where the first lead 1 and/or thesecond lead 2 has both of the recess 126 or 226 and the recess 85 isdescribed. However, the present disclosure is not limited to such aconfiguration. Each of the first lead 1 and the second lead 2 may haveonly one of the recess 126 (or 226) and the recess 85. Such aconfiguration also reduces separation of solder or formation of a crackin solder due to thermal stress, as compared with a conventionalconfiguration.

In the above embodiment, the third-lead terminal parts 320 do not haveany recesses that may correspond to the recess 126, the end-surfacerecess 127 and the recess 85 of the first-lead terminal part 120. Thisis because the third lead 3 is bonded to the circuit wiring 91 over alarge area of the mount-part back surface 312 so that separation betweenthe third-lead terminal-part back surface 322 and the solder 92, even ifoccurred, does not cause a significant problem. However, the third-leadterminal parts 320 may be formed with a recess corresponding to therecess 126, the end-surface recess 127 or the recess 85 of thefirst-lead terminal part 120.

In the above embodiment, the case where the first-lead terminal part120, the second-lead terminal parts 220 and the third-lead terminal part320 project from the sealing resin 8 is described, though the presentdisclosure is not limited thereto. The first-lead terminal-part endsurface 123, the second-lead terminal-part end surfaces 223 and thethird-lead terminal-part end surfaces 323 may be flush with the secondside surface of the resin side surface 83 or may be retreated from thesecond side surface 832. Also, the shape of each end surface may bevaried.

A semiconductor device A2 according to a second embodiment of thepresent disclosure is described below with reference to FIG. 17. In FIG.7, the elements that are identical or similar to those of thesemiconductor device A1 are denoted by the same reference signs, anddescriptions thereof are omitted. FIG. 17 is a perspective view of thesemiconductor device A2, which corresponds to FIG. 11 that shows thesemiconductor device A1 according to the first embodiment.

The semiconductor device A2 of the present embodiment differs from thesemiconductor device A1 in number of recesses 126 formed in thefirst-lead terminal-part back surface 122. In the present embodiment,four recesses are formed in the first-lead terminal-part back surface122. The outer edge of each recess 126 forms a closed shape within thefirst-lead terminal-part back surface 122.

In the present embodiment again, in bonding the first-lead terminal part120 to the circuit wiring 91 using the solder 92, the solder fills eachrecess 126, forming the filling part 923. Thus, the existence of therecesses 126 increases the bond area between the first-lead terminalpart 120 and the solder 92. This reduces formation of a crack in thesolder 92 or separation of the solder 92 from the first-leadterminal-part back surface 122 due to thermal stress. Provision of aplurality of recesses 126 (four recesses 126 in the illustrated example)enhances the effect of reducing crack formation or separation of thesolder 92.

The number of recesses 126 in the first-lead terminal-part back surface122 is not limited and may be two, three, or more than four. The numberof recesses 226 formed in each second-lead terminal-part back surface222 may also be varied.

A semiconductor device A3 according to a third embodiment of the presentdisclosure is described below with reference to FIG. 18. In FIG. 18, theelements that are identical or similar to those of the semiconductordevice A1 are denoted by the same reference signs, and descriptionsthereof are omitted. FIG. 18 is a perspective view of the semiconductordevice A3, which corresponds to FIG. 11 that shows the semiconductordevice A1 according to the first embodiment.

The semiconductor device A3 of the present embodiment differs from thesemiconductor device A1 in shape of the recess 126. The recess 226 inthe present embodiment is rectangular as viewed in the z direction andlocated at or near the center of the first-lead terminal-part backsurface 122. The outer edge of the recess 126 forms a closed shapewithin the first-lead terminal-part back surface 122.

In the present embodiment again, in bonding the first-lead terminal part120 to the circuit wiring 91 using the solder 92, the solder fills therecess 126, forming the filling part 923. Thus, the existence of therecess 126 increases the bond area between the first-lead terminal part120 and the solder 92. This reduces formation of a crack in the solder92 or separation of the solder 92 from the first-lead terminal-part backsurface 122 due to thermal stress.

Note that the shape of the recess 126 is not limited to that in theillustrated example. The shape of the recess 226 in each of thesecond-lead terminal-part back surfaces 222 may also be varied.

A semiconductor device A4 according to a fourth embodiment of thepresent disclosure is described below with reference to FIG. 19. In FIG.19, the elements that are identical or similar to those of thesemiconductor device A1 are denoted by the same reference signs, anddescriptions thereof are omitted. FIG. 19 is a perspective view of thesemiconductor device A4, which corresponds to FIG. 11 that shows thesemiconductor device A1 according to the first embodiment.

The semiconductor device A4 of the present embodiment has a recess 87,instead of the recess 126 of the semiconductor device A1. Specifically,instead of the recess 126, a groove 128 is formed in the first-leadterminal-part back surface 122. The groove 128 may extend in parallel tothe first-lead terminal-part end surface 123 from one end to the otherend of the first-lead terminal-part back surface 122 in the x direction.In forming the sealing resin in the manufacturing process, use is madeof a mold that is configured such that the groove 128 is not coveredwith the sealing resin. Thus, the resulting sealing resin 8 has interiorside surfaces 86 that are perpendicular to the groove 128. The innersurfaces of the groove 128 are exposed from the resin back surface 82 ofthe sealing resin 8. The recess 87 is defined by the groove 128 and theinterior side surfaces 86. The outer edge of the recess 87 forms aclosed shape within the resin back surface 82.

In the present embodiment again, in bonding the first-lead terminal part120 to the circuit wiring 91 using the solder 92, the solder fills therecess 87, forming the filling part 923. Thus, the existence of therecess 87 increases the bond area between the first-lead terminal part120 and the solder 92. This reduces formation of a crack in the solder92 or separation of the solder 92 from the first-lead terminal-part backsurface 122 due to thermal stress.

Note that a plurality of recesses 87 may be provided. The plurality ofrecesses can be formed by forming a plurality of grooves 128 in thefirst-lead terminal-part back surface 122. The recess 87 may be formedin the second-lead terminal-part back surfaces 222 as well.

A semiconductor device A5 according to a fifth embodiment of the presentdisclosure is described below with reference to FIG. 20. In FIG. 20, theelements that are identical or similar to those of the semiconductordevice A1 are denoted by the same reference signs, and descriptionsthereof are omitted. FIG. 20 is a perspective view of the semiconductordevice A5, which corresponds to FIG. 11 that shows the semiconductordevice A1 according to the first embodiment.

The semiconductor device A5 of the present embodiment differs from thesemiconductor device A1 in shape of the recess 85. Specifically, therecess 85 of this embodiment is semicircular as viewed in the zdirection and defined by the first-lead connecting-part back surface132, the first-lead terminal-part second end surface 124, and theinterior side surface 84 that is a curved surface. The outer edge of therecess 85 forms a closed shape within the resin back surface 82.

In the present embodiment again, in bonding the first-lead terminal part120 to the circuit wiring 91 using the solder 92, the solder fills therecess 85, forming the second solder fillet 922. This reduces formationof a crack in the solder or separation of the solder 92 from thefirst-lead terminal-part back surface 122 due to thermal stress.Moreover, according to the present embodiment, the boundary between theresin back surface 82 and the interior side surfaces 84 is curved. Sincethe boundary has no pointed portion, chipping of the sealing resin 8 atthe boundary is prevented.

Note that the shape of the recess 85 is not limited to that in theillustrated example. Additionally, the shape of the recess 85 on theinner side of each second-lead terminal part 220 in the y direction mayalso be varied.

A semiconductor device A6 according to a sixth embodiment of the presentdisclosure is described below with reference to FIG. 21. In FIG. 21, theelements that are identical or similar to those of the semiconductordevice A1 are denoted by the same reference signs, and descriptionsthereof are omitted. FIG. 21 is a perspective view of the semiconductordevice A6, which corresponds to FIG. 11 that shows the semiconductordevice A1 according to the first embodiment.

The semiconductor device A6 of the present embodiment differs from thesemiconductor device A1 in shape of the recess 85. In the presentembodiment, the first-lead connecting-part back surface 132 is notexposed from the resin back surface 82 but covered with the sealingresin 8. The recess 85 is defined by the first-lead terminal-part secondend surface 124 and the interior side surfaces 84. The outer edge of therecess 85 forms a closed shape within the resin back surface 82.

In the present embodiment again, since the first-lead terminal-partsecond end surface 124 is exposed, the second solder fillet 922 isformed in the recess 85 in bonding the first-lead terminal part 120 tothe circuit wiring 91 using the solder 92. This reduces formation of acrack in the solder or separation of the solder 92 from the first-leadterminal-part back surface 122 due to thermal stress.

A semiconductor device A7 according to a seventh embodiment of thepresent disclosure is described below with reference to FIG. 22. In FIG.22, the elements that are identical or similar to those of thesemiconductor device A1 are denoted by the same reference signs, anddescriptions thereof are omitted. FIG. 22 is a perspective view of thesemiconductor device A7, which corresponds to FIG. 11 that shows thesemiconductor device A1 according to the first embodiment.

The semiconductor device A7 of the present embodiment differs from thesemiconductor device A1 in configuration of the recess 85. In thepresent embodiment, the recess 85 is not arranged on the inner side ofthe first-lead terminal part 120 in they direction but arranged on eachside of the first-lead terminal part 120 in the x direction. Thefirst-lead terminal part 120 has a pair of first-lead terminal-part sidesurfaces 125. Each of the first-lead terminal-part side surfaces 125faces in the x direction and connects the first-lead terminal-part frontsurface 121 and the first-lead terminal-part back surface 122 to eachother. In forming the sealing resin in the manufacturing process, use ismade of a mold that is configured such that a part of each first-leadterminal-part side surface 125 is not covered with the sealing resin.Thus, the resulting sealing resin 8 has interior side surfaces 84 thatare perpendicular to the resin back surface 82 and interior backsurfaces 88 that are parallel to the resin back surface 82. Eachfirst-lead terminal-part side surface 125 is partially exposed from theresin back surface 82 of the sealing resin 8. The recesses 85 aredefined by the first-lead terminal-part side surfaces 125, the interiorside surfaces 84 of the sealing resin 8 and the interior back surfaces88. The outer edge of each recess 85 forms a closed shape within theresin back surface 82.

In the present embodiment again, since each of the first-leadterminal-part side surfaces 125 is partially exposed, the second solderfillet 922 is formed in each recess 85 in bonding the first-leadterminal part 120 to the circuit wiring 91 using the solder 92. Thisreduces formation of a crack in the solder 92 or separation of thesolder 92 from the first-lead terminal-part back surface 122 due tothermal stress. The configuration of the present embodiment isparticularly effective in reducing formation of a crack due to thermalstress in the x direction.

Note that the recess 85 may not be provided on each side but may beprovided on only one side of the first-lead terminal part 120 in the xdirection. Moreover, the recess 85 according to the first embodiment,which is provided on the outer side of the first-lead terminal part 120in the y direction, may be additionally provided. The recesses 85according to the seventh embodiment and the recess 85 according to thefirst embodiment may be connected to each other to provide a recess thatsurrounds the outer side in the y direction and each side in the xdirection of the first-lead terminal part 120.

A semiconductor device A8 according to an eighth embodiment of thepresent disclosure is described below with reference to FIG. 23. In FIG.23, the elements that are identical or similar to those of thesemiconductor device A1 are denoted by the same reference signs, anddescriptions thereof are omitted. FIG. 23 is a bottom view of thesemiconductor device A8, which corresponds to FIG. 4 that shows thesemiconductor device A1 according to the first embodiment.

The semiconductor device A8 of the present embodiment differs from thesemiconductor device A1 in configuration of the third lead 3. In thepresent embodiment, the dimension of the mount part 310 of the thirdlead 3 in the z direction is about a half of that of the third-leadterminal parts 320. The mount-part back surface 312 is not exposed fromthe resin back surface 82 of the sealing resin 8 and hence does notprovide a back-surface terminal. The third lead 3 does not include athird-lead thin part 330. In other words, the entirety of the mount part310 provides a third-lead thin part 330.

Each of the third-lead terminal parts 320 has the same configuration asthat of the first-lead terminal part 120. That is, each third-leadterminal part 320 further includes a third-lead terminal-part second endsurface 324, a recess 326 and an end-surface recess 327. The third-leadterminal-part second end surface 324 faces away from the third-leadterminal-part end surface 323, is exposed from the sealing resin 8 andis connected to the third-lead terminal-part back surface 322. Therecess 326 has the same configuration as that of the recess 126. Thatis, the recess 326 is formed in the third-lead terminal-part backsurface 322 and circular as viewed in the z direction. The end-surfacerecess 327 has the same configuration as that of the end-surface recess127. That is, the end-surface recess 327 is formed in the third-leadterminal-part end surface 323 and extends from one end to the other endof the third-lead terminal-part end surface 323 in the z direction.

The third lead 3 further includes third-lead connecting parts 340 thatconnect the mount part 310 and the third-lead terminal parts 320 to eachother. Each of the third-lead connecting parts 340 is connected to themount part 310 and a respective one of the third-lead terminal parts320. Each third-lead connecting part 340 is rectangular as viewed in thez direction. The thickness (i.e., the dimension in the z direction) ofthe third-lead connecting part 340 is about a half of the thickness ofthe third-lead terminal part 320 and the same as that of the mount part310. The third-lead connecting part 340 is formed by half etching, forexample. The third-lead connecting part 340 has a third-leadconnecting-part front surface 341 and a third-lead connecting-part backsurface 342. The third-lead connecting-part front surface 341 and thethird-lead connecting-part back surface 342 face opposite to each otherin the z direction. The third-lead connecting-part front surface 341 islocated on the back side of the sheet surface of FIG. 23 in the zdirection and is not shown in FIG. 23. The third-lead connecting-partfront surfaces 341, the mount-part front surface 311 and the third-leadterminal-part front surfaces 321 are flush and integral with each other.The third-lead connecting-part back surface 342 is located on the sheetsurface side of FIG. 23 in the z direction. The third-leadconnecting-part back surface 342 is flush with the mount-part backsurface 312 and located closer to the resin front surface 81 than thethird-lead terminal-part back surface 322 is. The third-leadconnecting-part back surface 342 is exposed from the resin back surface82 of the sealing resin 8 and connected to the third-lead terminal-partsecond end surface 324. The third-lead connecting-part back surface 342may not be entirely exposed from the sealing resin 8, and only a part ofthe third-lead connecting-part back surface 342 may be exposed from thesealing resin 8.

In forming the sealing resin in the manufacturing process, use is madeof a mold that is configured such that the third-lead connecting-partback surface 342 and the third-lead terminal-part second end surface 324are not covered with the sealing resin. Thus, the resulting sealingresin 8 has interior side surfaces 84 that are perpendicular to thethird-lead connecting-part back surface 342 and that surround thethird-lead connecting-part back surface 342. The third-leadconnecting-part back surface 342 and the third-lead terminal-part secondend surface 324 are exposed from the resin back surface 82 of thesealing resin 8. Thus, on the inner side of each third-lead terminalpart 320, a recess 85 is defined by the third-lead connecting-part backsurface 342, the third-lead terminal-part second end surface 324 and theinterior side surfaces 84 of the sealing resin 8.

According to the present embodiment, since the third lead 3 has recesses326 formed in the third-lead terminal-part back surfaces 322, formationof a crack in the solder 92 or separation of the solder 92 from thethird-lead terminal-part back surfaces 322 due to thermal stress isreduced. Further, recesses 85 are formed on the inner side of thethird-lead terminal parts 320. This contributes to reduction offormation of a crack in the solder 92 or separation of the solder 92from the third-lead terminal-part back surfaces 322 due to thermalstress. Moreover, the third lead 3 has end-surface recesses 327 formedin the third-lead terminal-part end surfaces 323. This also contributesto reduction of formation of a crack in the solder or separation of thesolder 92 from the third-lead terminal-part back surfaces 322 due tothermal stress.

A semiconductor device A9 according to a ninth embodiment of the presentdisclosure is described below with reference to FIG. 24. In FIG. 24, theelements that are identical or similar to those of the semiconductordevice A1 are denoted by the same reference signs, and descriptionsthereof are omitted. FIG. 24 is a bottom view of the semiconductordevice A9, which corresponds to FIG. 4 that shows the semiconductordevice A1 according to the first embodiment.

The semiconductor device A9 according to the present embodiment differsfrom the semiconductor device A1 in that the first lead 1 and the secondleads 2 are disposed on each side of the third lead 3 in the ydirection. In the present embodiment, the third lead 3 is disposed atthe center of the semiconductor device A1 in the y direction, and thethird-lead terminal parts 320 are not disposed at the end surfaces ofthe mount part 310 in the y direction. On each side of the third lead 3in the y direction, the first lead 1 and the second leads 2 aredisposed.

The present embodiment provides the same effects as those of the firstembodiment.

A semiconductor device A10 according to a tenth embodiment of thepresent disclosure is described below with reference to FIG. 25. In FIG.25, the elements that are identical or similar to those of thesemiconductor device A1 are denoted by the same reference signs, anddescriptions thereof are omitted. FIG. 25 is an enlarged sectional viewshowing a part of a semiconductor device A10, which corresponds to FIG.10 that shows the semiconductor device A1 according to the firstembodiment.

The semiconductor device A10 according to the present embodiment differsfrom the semiconductor device A1 in configuration of the first lead 1.In the present embodiment, the wire bonding part 110 and the first-leadconnecting part 130 of the first lead 1 are not formed by half etchingbut formed by stamping. That is, the wire bonding part 110, thefirst-lead terminal part 120 and the first-lead connecting part 130 areprovided by forming the first lead 1 by bending a plate-like memberhaving a constant thickness. Accordingly, the thickness of the wirebonding part 110 and the first-lead connecting part 130 are the same asthat of the first-lead terminal part 120. The wire bonding part 110 islocated closer to the resin front surface 81 than the first-leadterminal part 120 is. The wire bonding part 110 and the first-leadterminal part 120 are connected by an inclined part, which provides thefirst-lead connecting part 130. A recess 85 is defined by the first-leadconnecting-part back surface 132 and the interior side surfaces 84 ofthe sealing resin 8. Note that the recess 126 may be formed during thestamping process, which is preferable for enhanced efficiency.

In the present embodiment again, in bonding the first-lead terminal part120 to the circuit wiring 91 using the solder 92, the solder fills therecess 85, forming the second solder fillet 922. This reduces formationof a crack in the solder or separation of the solder 92 from thefirst-lead terminal-part back surface 122 due to thermal stress.

A semiconductor device A11 according to an eleventh embodiment of thepresent disclosure is described below with reference to FIGS. 26-28. InFIGS. 26-28, the elements that are identical or similar to those of thesemiconductor device A1 are denoted by the same reference signs, anddescriptions thereof are omitted. FIG. 26 is a front view showing thesemiconductor device A11, which corresponds to FIG. 3 that shows thesemiconductor device A1 according to the first embodiment. FIG. 27 is abottom view showing the semiconductor device A11, which corresponds toFIG. 4 that shows the semiconductor device A1 according to the firstembodiment. FIG. 28 is a perspective view showing the semiconductordevice A11, which corresponds to FIG. 11 that shows the semiconductordevice A1 according to the first embodiment.

The semiconductor device A11 according to the present embodiment differsfrom the semiconductor device A1 in configuration of the end-surfacerecess 127, 227 and the third lead 3. Further, the semiconductor deviceA11 does not have a recess 85. In the present embodiment, theend-surface recess 127 does not extend from one end to the other end ofthe first-lead terminal-part end surface 123 in the z direction butextends from one end (lower end in FIG. 26) to an intermediate point inthe first-lead terminal-part end surface 123. The end-surface recess 127is semicircular as viewed in the y direction. The end-surface recess 127can be made by forming a semi-spherical (or substantially spherical)recess instead of a through-hole in a lead frame followed by cutting thelead frame at the (semi-) spherical recess. The end-surface recesses 227have the same configuration as the end-surface recess 127. As shown inFIG. 27, in the present embodiment, each of the third-lead terminal-partback surface 322 of the third lead 3 has a curved shape, so that theregion of the third lead 3 that is exposed from the resin back surface82 has a shape with curved recess extending inward from the third-leadterminal-part end surfaces 323. As will be understood from FIGS. 27 and28, the semiconductor device A11 does not have a recess 85.

In the present embodiment, the first-lead terminal-part end surface 123has the end-surface recess 127 that extends from one end (the end closerto a circuit board to which the device is to be mounted) to anintermediate point of the first-lead terminal-part end surface 123 inthe z direction. The end-surface recess 127 having such a configurationallows the first solder fillet 921 to be formed on the outer side of thefirst-lead terminal part 120 in they direction in the process ofmounting the first-lead terminal part 120 to the circuit wiring 91 usingsolder 92. This reduces formation of a crack in the solder 92 orseparation of the solder 92 from the first-lead terminal-part backsurface 122 due to thermal stress. Moreover, although the semiconductordevice A11 does not have the recess 85, it has the recess 126. Inbonding the first-lead terminal part 120 to the circuit wiring 91 usingthe solder 92, the solder fills the recess 126, forming the filling part923. This also reduces formation of a crack in the solder 92 orseparation of the solder 92 from the first-lead terminal-part backsurface 122 due to thermal stress.

A semiconductor device A12 according to a twelfth embodiment of thepresent disclosure is described below with reference to FIGS. 29 and 30.In FIGS. 29 and 30, the elements that are identical or similar to thoseof the semiconductor device A1 are denoted by the same reference signs,and descriptions thereof are omitted. FIG. 29 is a bottom view of thesemiconductor device A12, which corresponds to FIG. 4 that shows thesemiconductor device A1 according to the first embodiment. FIG. 30 is aperspective view showing the semiconductor device A12, which correspondsto FIG. 11 that shows the semiconductor device A1 according to the firstembodiment.

The semiconductor device A12 has the configuration obtained by addingthe recesses 85 to the configuration of the semiconductor device A11according to the eleventh embodiment. That is, the semiconductor deviceA12 differs from the semiconductor device A1 in shape of the end-surfacerecesses 127, 227 and shape of the third lead 3.

The semiconductor device A12 according to the present embodiment furtherincludes recesses 85 in addition to the components or parts of thesemiconductor device A11. In the present embodiment again, in bondingthe first-lead terminal part 120 to the circuit wiring 91 using thesolder 92, the solder fills the recess 85, forming the second solderfillet 922. This reduces formation of a crack in the solder 92 orseparation of the solder 92 from the first-lead terminal-part backsurface 122 due to thermal stress.

The present disclosure is applicable to various semiconductor devices ofa surface-mounted type, regardless of the type, number and arrangementof the semiconductor elements, the number and arrangement of the leads,and the number and arrangement of the terminal parts. The presentdisclosure is especially effective when the bond area between a terminalpart exposed from the sealing resin and a circuit wiring is small.

The semiconductor device according to the present disclosure is notlimited to the foregoing embodiments. The specific structure of eachpart of the semiconductor device according to the present disclosure maybe varied in various ways.

Clause 1.

A semiconductor device comprising:

a semiconductor element;

a first lead electrically connected to the semiconductor element;

a sealing resin that covers the semiconductor element and a part of thefirst lead, the sealing resin including a resin front surface, a resinback surface opposite to the resin front surface in a thicknessdirection, and a resin side surface connecting the resin front surfaceand the resin back surface to each other; and

at least one recess formed in a surface that is flush with the resinback surface,

wherein the recess comprises apart of the first lead that is exposedfrom the resin back surface, and

the recess has an outer edge that forms a closed shape, as viewed in thethickness direction, within a region that includes the resin backsurface and the first lead.

Clause 2.

The semiconductor device according to clause 1, wherein the first leadincludes a terminal part that has a terminal-part back surface and aterminal-part end surface, the terminal-part back surface being flushwith the resin back surface, the terminal-part end surface being exposedfrom the resin side surface, and the recess is formed in theterminal-part back surface.

Clause 3.

The semiconductor device according to clause 2, wherein the recess iscircular as viewed in the thickness direction.

Clause 4.

The semiconductor device according to clause 2, wherein the recess isrectangular as viewed in the thickness direction.

Clause 5.

The semiconductor device according to clause 1, wherein the first leadincludes a terminal part that has a terminal-part back surface and aterminal-part end surface, the terminal-part back surface being flushwith the resin back surface, the terminal-part end surface being exposedfrom the resin side surface,

the terminal-part back surface is formed with a groove that is parallelto the terminal-part end surface, and

the recess is formed by the groove and the sealing resin.

Clause 6.

The semiconductor device according to any one of clauses 2-5, whereinthe at least one recess comprises a plurality of recesses.

Clause 7.

The semiconductor device according to clause 1, wherein the first leadincludes a terminal part and a connecting part connected to the terminalpart, the terminal part including a terminal-part back surface that isflush with the resin back surface, a terminal-part end surface exposedfrom the resin side surface, and a terminal-part second end surfacefacing away from the terminal-part end surface,

the connecting part includes a connecting-part back surface facing in adirection in which the terminal-part back surface faces and locatedcloser to the resin front surface than the terminal-part back surface isin the thickness direction, and

the recess is formed by the connecting-part back surface, theterminal-part second end surface and the sealing resin.

Clause 8.

The semiconductor device according to clause 7, wherein an entirety ofthe connecting-part back surface is exposed from the resin back surface.

Clause 9.

The semiconductor device according to clause 7 or 8, wherein the recessis rectangular as viewed in the thickness direction.

Clause 10.

The semiconductor device according to clause 7, wherein the recess issemicircular as viewed in the thickness direction.

Clause 11.

The semiconductor device according to any one of clauses 2-10, whereinthe terminal-part end surface projects from the resin side surface.

Clause 12.

The semiconductor device according to any one of clauses 2-10, whereinthe terminal-part end surface is flush with the resin side surface.

Clause 13.

The semiconductor device according to any one of clauses 2-12, whereinthe terminal-part end surface includes an end-surface recess extendingin the thickness direction.

Clause 14.

The semiconductor device according to any one of clauses 1-13, furthercomprising a plating layer formed in at least a part of the recess.

Clause 15

The semiconductor device according to any one of clauses 1-14, furthercomprising: a second lead electrically connected to the semiconductorelement; and a third lead on which the semiconductor element is mounted,wherein the first lead and the second lead are arranged between thethird lead and the resin side surface.

Clause 16.

The semiconductor device according to clause 15, wherein thesemiconductor element includes a surface that faces the third lead andis formed with an electrode electrically connected to the the thirdlead.

Clause 17.

The semiconductor device according to clause 16, wherein thesemiconductor element comprises a transistor.

The invention claimed is:
 1. A semiconductor device comprising: asemiconductor element; a first lead electrically connected to thesemiconductor element; a sealing resin that covers the semiconductorelement and a part of the first lead, the sealing resin including aresin front surface, a resin back surface opposite to the resin frontsurface in a thickness direction, and a resin side surface connectingthe resin front surface and the resin back surface to each other; and atleast one recess formed in a surface that is flush with the resin backsurface, wherein the recess comprises a part of the first lead that isexposed from the resin back surface, the recess has an outer edge thatforms a closed shape, as viewed in the thickness direction, within aregion that includes the resin back surface and the first lead, thefirst lead includes a terminal part and a connecting part connected tothe terminal part, the terminal part including a terminal-part backsurface that is flush with the resin back surface, a terminal-part endsurface exposed from the resin side surface, and a terminal-part secondend surface facing away from the terminal-part end surface, theconnecting part includes a connecting-part back surface facing in adirection in which the terminal-part back surface faces and locatedcloser to the resin front surface than the terminal-part back surface isin the thickness direction, and the recess is formed by theconnecting-part back surface, the terminal-part second end surface andthe sealing resin.
 2. The semiconductor device according to claim 1,wherein the recess is rectangular as viewed in the thickness direction.3. The semiconductor device according to claim 1, wherein theterminal-part back surface is formed with a groove that is parallel tothe terminal-part end surface.
 4. The semiconductor device according toclaim 1, wherein an entirety of the connecting-part back surface isexposed from the resin back surface.
 5. The semiconductor deviceaccording to claim 1, wherein the recess is semicircular as viewed inthe thickness direction.
 6. The semiconductor device according to claim1, wherein the terminal-part end surface projects from the resin sidesurface.
 7. The semiconductor device according to claim 1, furthercomprising a plating layer formed in at least a part of the recess. 8.The semiconductor device according to claim 1, further comprising: asecond lead electrically connected to the semiconductor element; and athird lead on which the semiconductor element is mounted, wherein thefirst lead and the second lead are arranged between the third lead andthe resin side surface.
 9. A semiconductor device, comprising: asemiconductor element; a first lead electrically connected to thesemiconductor element; a sealing resin that covers the semiconductorelement and a part of the first lead, the sealing resin including aresin front surface, a resin back surface opposite to the resin frontsurface in a thickness direction, and a resin side surface connectingthe resin front surface and the resin back surface to each other; and atleast one recess formed in a surface that is flush with the resin backsurface, wherein the recess comprises a part of the first lead that isexposed from the resin back surface, the recess has an outer edge thatforms a closed shape, as viewed in the thickness direction, within aregion that includes the resin back surface and the first lead, thefirst lead includes a terminal part that has a terminal-part backsurface and a terminal-part end surface, the terminal-part back surfacebeing flush with the resin back surface, the terminal-part end surfacebeing exposed from the resin side surface, and the recess is formed inthe terminal-part back surface, and the terminal-part end surfaceincludes an end-surface recess extending in the thickness direction. 10.The semiconductor device according to claim 8, wherein the semiconductorelement includes a surface that faces the third lead and is formed withan electrode electrically connected to the the third lead.
 11. Thesemiconductor device according to claim 10, wherein the semiconductorelement comprises a transistor.